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Recessively inherited ovalocytosis in coastal Melanesians is associated with widespread, but selective, depression of blood group antigens in homozygotes, who comprise about 15% of these populations. It is suggested that a membrane anomaly exists, and that the series of depressed determinants all depend, for their full expression, upon the same membrane component(s), the proper synthesis of which is being genetically affected. Affected antigens would thus be associated by position and/or structure. Antigens subject to depression include IT, IF, LW,D,C,e,S,s,U,Kpb,JKa,JKb,Xga,Wrb,Scl and Ena, which are simultaneously affected when present on oval cells. Reactivity of A1,ID,i,P1,M,N,Lub,k,Fya,Coa, Vel and Gea appears to be within the normal range on depressed cells, as does sialic acid content. Indirect evidence suggests that Z (associated with S and s) is among the depressed series, while NA and Leb are not. High H variants, common among Melanesians, seem absent among depressed bloods, and when such variants were excluded, H, A and B did not appear subject to depression. The distribution pattern of ovalocytosis suggests that it may confer some selective advantage in the tropical coastal environment. The findings also have implications concerning population genetic work in New Guinea.

Melanesians of groups O, A1 and B all show greater variation of H antigen strength than do Caucasians. This is least marked in O bloods. Although the average H content of Melanesian and Caucasian samples did not differ significantly, 10% of O and over 20% of A1 and B bloods from coastal Austronesian speakers had higher H than was found among Caucasians, There is evidence that some non-Austronesian populations in New Guinea have twice this incidence of A1 high H. Melanesian and Bantu H, A1 and B genes appear to function similarly, in that their B genes act more effectively than Caucasian, their A1 genes less so, while H produces greater variation. It is suggested that this gene interaction, rather than the significantly greater availability of H or substrate in the Bantu, causes the observed variations from the Caucasian pattern found in the other races. Subjects with selective antigenic depression were excluded from the comparative studies, but the relevance of this phenomenon to apparent H content in Melanesians is discussed.

Two different Melanesian antibodies demonstrated, by blocking tests and their reaction patterns, steric interaction of S, s and U components. The antigen(s) detected, designated Ux and Uz, may represent differing conformations, genetically determined, of certain U, S and s structures. Of 1,000 Caucasian bloods, 3 had very marked enhancement of Ux. Family studies are presented. In one such blood, abnormal steric interaction of D with s and U was indicated. Melanesian population studies show that Ux and Uz are among the antigens depressed in recessive ovalocytosis. The linkage disequilibria affecting MNSs and SsUz are inter-related, the associations being of SUz with Caucasian M and Melanesian N.

The results of blood group surveys on a number of linguistic groups inhabiting contiguous areas within the Goilala sub-district of the Central District, the southern part of the Morobe District and the Northern District are reported. Altogether about 1900 subjects were tested, but the extent of testing varied. Red cell enzyme and serum protein systems were also investigated in two groups. Similarities and dissimilarities of blood group distributions are noted, as also are some possible gene gradients among peoples living to the north of the main divide. Two groups, the Kuni/Tauade of the Goilala sub-district, and the Roro/Kovio living towards the Papuan Gulf coast seem well distinguished from the remainder. Genetic distances were calculated for five populations north of the divide, and agree with the geographical and linguistic situation. The Weri people of the middle Waria provided an example of Hp 2-1 modified, two examples of the MDH.NG.1 variant and one of AK 2-1.

A series of blood samples from four villages in the Jimi Valley, Western New Guinea Highlands, has been tested for genetic variation in blood group, serum protein, and red cell enzyme systems. Polymorphic variation was present for the AB0, MNS, P, and Rh blood group systems, for the Hp and Tf serum protein systems, and for the acid phosphatase, 6-PGD, PGM, MDH, and ADA enzyme systems. One each of the following variants was detected: Ge(a-), G6PD deficient, AK 2-1 and PHI 7-1 or 8-1. All samples tested were Cw-, K-, Kp(a-), Wr(a-), Fy(a+ b-), Rd-, and LDH normal. Genetic distance analysis places the Jimi Valley populations closer to peoples of the Chimbu-Chuave and Wahgi-Hagen areas than to the Maring people of the Simbai Valley to the north.

A distinctive type of hereditary ovalocytosis has been found in Papua New Guinea and a few areas of Southeast Asia. Its main features include a high incidence among tropical lowland dwellers, autosomal recessive inheritance, specific depression of a number of red cell antigens, a characteristic morphology in blood films, and an effect on the erythrocyte sedimentation rate. Speculation has occurred as to whether the high incidence of ovalocytosis in malarious areas may be related to a selective advantage possessed by ovalocytics with regard to severe malaria. Preliminary data tend to support this hypothesis, but the evidence is not conclusive and much further work is needed.

Polynesian O bloods from Samoans and Tokelau Islanders have the same mean H reactivity as Caucasian, and their A1 bloods the same A1 content. However, Polynesian A1 bloods have significantly greater H reactivity than Caucasian, and the Tokelau Islanders also showed enhanced A and IT. It is suggested that the Polynesian AHI molecular conformation must differ from the Caucasian pattern, providing an arrangement of antigen sites more favourable to some antigen-antibody reactions.

A series of 1,187 blood samples from eight population groups in the Eastern Highlands of Papua New Guinea were tested for genetic variation in blood groups, serum proteins and red cell enzyme systems. The populations belonged to the language groups Gahuku-Asarc-Bena Bena, Kamano, Yagaria, Keiagana, Fore, Agarabe, Auyana and Tairora. Polymorphic variation was found in the ABO, MNS, P1, Rh, Hp, Tf, SEP, 6-PGD, ADA, MDH, and PGM genetic systems. East to West variation was shown in the language groups; the O, S, R2, and R0 genes increase in frequency from East to West and the A, R1, and M genes decrease in the same direction. In the East higher frequencies were found for the Du antigen, for the PGM21 gene and for a PGM second locus variant. The MDH 3 variant was found in all the populations, its highest value being in the Tairora.

Blood samples from the Waskia and Takia populations of Karkar Island, Papua New Guinea, and other nearby mainland populations, were tested for genetic variation in blood group, serum protein and red cell enzyme systems. Polymorphic variation was present in the ABO, P, MNS, Rh, Lewis, Duffy, Kidd and Gerbich blood group systems, in the Hp and Tf serum protein systems, and in the acid phosphatase, 6-PGD, ADA, PGM, MDH, and G-6-PD enzyme systems. A small number of variants was found in other systems: there were 4 Lu(a+), 1 Kp(a+), 2 C variants in the acid phosphatase system, 6 LDH variants, 1 ADA3-1 and 1 AK2-1 sample. All samples were negative for the red cell antigens Cw, Vw, He, K, Jsa, Dia, Wra, Rd and Marriott, and no variation was observed in the PHI enzyme system. The results are discussed in relation to those obtained on other Papua New Guinea populations.

101 Samoans living in New Zealand, of whom 77 had no known non-Samoan ancestry, have been typed for nine blood group systems, four serum protein and 23 red cell enzyme systems, for haemoglobin variants and antigens at the HLA A nad B loci. The frequencies of genes in these various systems suggest that Samoans fall partly into an island Melanesian-Micronesian pattern, and partly are unique. Their uniqueness is most distinctive for the HLA system.

Ninety-six Western Samoan volunteers were examined for the presence of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs). Seventy-two volunteers were full blooded Samoans and four were found to be asymptomatic carriers of HBsAg. No mixed blood volunteers had detectable HBsAg by either haemagglutination or radioimmunoassay techniques. Fifty of the 72 full blooded Samoans had anti-HBs detectable by radioimmunoassay. Eight of these reactions were only weakly positive. Seventeen of the 24 mixed blood volunteers had detectable anti-Hbs. All were Samoan born. This study suggests that Samoan born Somoans should provide a valuable source of anti-HBs if New Zealand preparation of this antibody is contemplated.